The invention is directed to a method for inserting an asynchronous 139,264 kbits/s signal according to CCITT recommendation G.754 into the pulse frame of a 155,520 kbit/s signal according to the CCITT recommendations G.707, G.708 and G.709 having a virtual container composed of 9 series each of which first contains 1 byte for a route header and a following, further 260 bytes.
The periodical "Telecommunications", March 1988, pages 63, 65 and 66 describes a synchronous optical network SONET having network node interfaces NNI for international use. This system operates with a hierarchy of digital signals STM-1 having a byte rate of 155,520 kbit/s, STM-4 having a byte rate of 622,080 kbit/s and potentially further digital signals such as STM-8, STM-12 and STM-16. A pulse frame is allocated to each of these digital signals. Digital signals having a lower byte rate of the European, the Japanese or the US hierarchy can be inserted into the pulse frame of the digital signal STM-1.